September 2016
Intermediate to advanced
989 pages
24h 10m
English
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Avoiding page faults in a real-time application
A page fault occurs when an application reads or writes memory that is not committed to physical memory. It is impossible (or very hard) to predict when a page fault will happen so they are another source of non-determinism in computers.
Fortunately, there is a function that allows you to commit all memory for a process and lock it down so that it cannot cause a page fault. It is mlockall(2). These are its two flags:
MCL_CURRENT: locks all pages currently mappedMCL_FUTURE: locks pages that are mapped in later
You usually call mlockall(2) during the start up of the application with both flags set to lock all current and future memory mappings.
Tip
Note that MCL_FUTURE is not magic in that there will still ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.